Compound bows are a relatively recent development. It has been reported that the first patent on a compound bow is U.S. Pat. No. 3,486,495 issued 30 Dec. 1969 to H. W. Allen.
Modern compound bows are instruments of considerable sophistication and not insignificant complexity.
A conventional bow of this type has a rigid riser with a grip for the archer and flexible limbs extending in opposite directions from the ends of the riser. A rotatable cam and a wheel (single cam bow) or two rotatable cams (double cam and hybrid cam bows) are mounted to and move with the tips of the flexible bow limbs as the bow is drawn and as the bow string subsequently released.
A bow string is connected between the cams, which rotate in opposite directions when the bow is drawn. As the bow is drawn, the bow string moves away from the riser of the bow; and the bow limbs are bent or flexed, storing potential energy which is converted to kinetic energy and used to accelerate the arrow when the bow string is released.
In the almost 40 years since the Allen patent was issued, many compound bow improvements have been made. Nevertheless, the search for a better compound bow continues.